Cardiovascular pressure annotations and logbook

ABSTRACT

A system comprises an external medical device configured to communicate with a first implantable medical device (IMD). The external medical device includes a communication circuit and a display. The communication circuit is configured to receive information associated with cardiovascular pressure from the IMD. The external medical device is configured to annotate a waveform on the display to indicate one or more events associated with cardiovascular pressure.

FIELD OF THE INVENTION

The field generally relates to implantable medical devices and, inparticular, but not by way of limitation, to systems and methods formonitoring a hemodynamic parameter of a subject.

BACKGROUND

Implantable medical devices (IMDs) are devices designed to be implantedinto a patient. Some examples of these devices include cardiac functionmanagement (CFM) devices such as implantable pacemakers, implantablecardioverter defibrillators (ICDs), cardiac resynchronization devices,and devices that include a combination of such capabilities. The devicesare typically used to treat patients using electrical or other therapyor to aid a physician or caregiver in patient diagnosis through internalmonitoring of a patient's condition. The devices may include one or moreelectrodes in communication with one or more sense amplifiers to monitorelectrical heart activity within a patient, and often include one ormore sensors to monitor one or more other internal patient parameters.Other examples of implantable medical devices include implantablediagnostic devices, implantable drug delivery systems, or implantabledevices with neural stimulation capability.

Additionally, some IMDs detect events by monitoring one or moreelectrical heart activity signals. In addition to electrical events, CFMdevices may measure and monitor one or more hemodynamic parametersrelated to heart chamber filling or contraction. These parameters mayprovide an indication of the metabolic need of a patient for aparticular level of cardiac output, for example. The parameters may beuseful to track the progression of disease, such as congestive heartfailure, for example. Measuring and monitoring the parameters may alsobe useful to detect a sudden episode such as acute myocardial ischemia.As technology used in IMDs increases, the devices are able to collectdata from multiple types of sensors. However, this can complicate thetask of data management for caregivers.

SUMMARY

This document relates generally to systems, devices, and methods forassessing the metabolic demand of a patient as indicated throughcardiovascular pressure. A system example includes an external medicaldevice configured to communicate with an implantable medical device(IMD). The external medical device includes a communication circuit anda display. The communication circuit is configured to receiveinformation associated with cardiovascular pressure from the IMD. Theexternal medical device is configured to annotate a waveform on thedisplay to indicate one or more events associated with cardiovascularpressure.

Another system example includes an IMD. The IMD includes an implantablecardiovascular pressure sensor interface unit, an implantable cardiacsignal sensing circuit, a memory, and a trigger detector. The triggerdetector is coupled to the cardiovascular pressure interface unit, theimplantable cardiac signal sensing circuit, and the memory. Thecardiovascular pressure interface unit is configured to receive a sensorsignal associated with cardiovascular pressure of a subject. Theimplantable cardiac signal sensing circuit is configured to receive atleast one sensed intrinsic heart signal from at least one implantableelectrode. The trigger detector is configured to store at least one ofcardiovascular pressure sensor signal data and detected cardiovascularpressure-related event annotations in response to a triggering eventdetected from a sensed electrical cardiac signal.

A method example includes communicating information associated withcardiovascular pressure from an IMD to an external device, andannotating a displayed waveform on the external device to indicate oneor more detected events associated with cardiovascular pressure.

Another method example includes sensing one or more cardiac signalsrepresentative of intrinsic cardiac activity of a subject using an IMD,sensing cardiovascular pressure of the subject, and storing at least oneof sampled cardiovascular pressure sensor signal data and detectedcardiovascular pressure-related event annotations in the IMD in responseto a detected triggering event detected from a sensed cardiac signal.

This summary is intended to provide an overview of the subject matter ofthe present patent application. It is not intended to provide anexclusive or exhaustive explanation of the invention. The detaileddescription is included to provide further information about the subjectmatter of the present patent application.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of portions of a system that uses an IMD.

FIG. 2 illustrates an IMD coupled by one or more leads to a heart.

FIG. 3 shows an example of a representation of a cardiovascular pressurewaveform obtained from a pulmonary artery pressure sensor signal.

FIG. 4 is a block diagram of portions of an example of a system tomonitor cardiovascular pressure of a subject.

FIG. 5 is a block diagram of portions of another example of a system tomonitor cardiovascular pressure of a subject.

FIG. 6 is a block diagram of portions of another example of a system tomonitor cardiovascular pressure of a subject.

FIG. 7 is a block diagram of portions of another example of a system tomonitor cardiovascular pressure of a subject.

FIG. 8 shows an example of a flow diagram of a method to monitorcardiovascular pressure of a subject.

FIG. 9 shows another example of a flow diagram of a method to monitorcardiovascular pressure of a subject.

DETAILED DESCRIPTION

The following detailed description includes references to theaccompanying drawings, which form a part of the detailed description.The drawings show, by way of illustration, specific embodiments in whichthe invention may be practiced. These embodiments, which are alsoreferred to herein as “examples,” are described in enough detail toenable those skilled in the art to practice the invention. Theembodiments may be combined, other embodiments may be utilized, orstructural, logical and electrical changes may be made without departingfrom the scope of the present invention. The following detaileddescription is, therefore, not to be taken in a limiting sense, and thescope of the present invention is defined by the appended claims andtheir equivalents.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one. In this document, the term“or” is used to refer to a nonexclusive or, such that “A or B” includes“A but not B,” “B but not A,” and “A and B,” unless otherwise indicated.Furthermore, all publications, patents, and patent documents referred toin this document are incorporated by reference herein in their entirety,as though individually incorporated by reference. In the event ofinconsistent usages between this document and those documents soincorporated by reference, the usage in the incorporated reference(s)should be considered supplementary to that of this document; forirreconcilable inconsistencies, the usage in this document controls.

FIG. 1 is a block diagram of portions of a system 100 that uses animplantable medical device (IMD) 110. As one example, the system 100shown is used to treat a cardiac arrhythmia. The IMD 110 typicallyincludes an electronics unit coupled by a cardiac lead 108, oradditional leads, to a heart 105 of a patient 102 or subject, orotherwise associated with the heart 105. Examples of IMD 110 include,without limitation, a, pacemaker, a cardioverter, a defibrillator, acardiac resynchronization therapy (CRT) device, and other cardiacmonitoring and therapy delivery devices, including cardiac devices thatinclude or work in coordination with one or more neuro-stimulatingdevices, drugs, drug delivery systems, or other therapies. System 100also typically includes an IMD programmer or other external device 170that communicates one or more wireless signals 160 with the IMD 110,such as by using radio frequency (RF) or one or more other telemetrymethods.

Cardiac lead 108 includes a proximal end that is coupled to IMD 110 anda distal end, coupled by one or more electrodes to one or more portionsof a heart 105. The electrodes typically deliver cardioversion,defibrillation, pacing, or resynchronization therapy, or one or morecombinations thereof to at least one chamber of the heart 105. Theelectronics unit of the IMD 110 typically includes components that areenclosed in a hermetically-sealed canister or “can.” Other electrodesmay be located on the can, or on an insulating header extending from thecan, or on other portions of IMD 110, such as for providing pacingenergy, defibrillation energy, or both, in conjunction with the one ormore electrodes disposed on or around a heart 105. The lead 108 or leadsand electrodes are also typically used for sensing intrinsic or otherelectrical activity of the heart 105.

An IMD 110 may include one or more of the features, structures, methods,or combinations thereof described herein. For example, a cardiac monitoror a cardiac stimulator may be implemented to include one or more of thedescribed features and processes. It is intended that such a monitor,stimulator, or other implantable or partially implantable device neednot include all of the features described herein, but may be implementedto include one or more selected features that may provide one or moreunique structures or functionality. Such a device may be implemented toprovide a variety of therapeutic or diagnostic functions.

FIG. 2 illustrates an IMD 110 coupled by one or more leads 108 to heart105. Heart 105 includes a right atrium 200A, a left atrium 200B, a rightventricle 205A, and a left ventricle 205B. In this example, the lead 108includes one or more electrodes (electrical contacts, such as ringelectrode 225 and tip electrode 230) disposed in a right ventricle 205Aof heart 105 for sensing one or more intrinsic signals, or deliveringpacing therapy, or both, to the right ventricle 205A. In this example,the lead 108 also includes one or more electrodes configured forplacement in the right atrium 200A, such as ring electrode 235 and ringelectrode 240, for sensing one or more intrinsic electrical cardiacsignals, delivering pacing therapy, or both sensing signals anddelivering pacing therapy. Sensing and pacing allows the IMD 110 toadjust timing of the heart chamber contractions. For example, IMD 110can adjust the timing of ventricular contractions with respect to thetiming of atrial contractions delay by sensing a contraction in theright atrium 200A and pacing the right ventricle 205A at the desiredatrial-ventricular (AV) delay time. The IMD also includes can or housingelectrode 250 formed on the IMD can or housing 245, and header electrode260 formed on the IMD header 255.

The IMD 110 optionally also includes additional leads or electrodes,such as for delivering atrial cardioversion, atrial defibrillation,ventricular cardioversion, ventricular defibrillation, or one or morecombinations thereof to heart 105. Optionally, IMD 110 includes anadditional cardiac lead that includes ring electrodes for placement in acoronary vein extending along a wall of the left ventricle 205B. A leadplaced in the left ventricle 205B and a lead placed in the rightventricle 205A may be used to optionally provide resynchronizationtherapy to the heart 105. Defibrillation electrodes typically havelarger surface areas than pacing electrodes in order to handle thelarger energies involved in defibrillation. Other forms of electrodesinclude meshes and patches, which may be applied to one or more portionsof heart 105, or which may be implanted in one or more other areas ofthe body to help “steer” electrical current produced by IMD 110. TheIMDs may be configured with a variety of electrode arrangements,including transveous, endocardial, or epicardial electrodes (e.g.,intrathoracic electrodes), or subcutaneous, non-intrathoracicelectrodes, such as can, header, or indifferent electrodes, orsubcutaneous array or lead electrodes (e.g., non-intrathoracicelectrodes).

Cardiovascular pressure includes right atrial pressure, left atrialpressure, right ventricular pressure, left ventricular pressure, venouspressure, mixed venous pressure, central venous pressure, peripheralvenous pressure, pulmonary venous pressure, and pulmonary arterialpressure. Pulmonary arterial (PA) pressure includes the pressure withina pulmonary artery due to blood leaving the right ventricle through thepulmonary valve and going to the lungs.

Measurements relating to cardiovascular pressure can provide valuableinformation in assessing the hemodynamic health of a patient or subject.For example, knowledge of a subject's cardiovascular pressure is usefulin diagnosing pulmonary hypertension, congestive heart failure (CHF), orheart failure (HF) decompensation. A cardiovascular pressure sensor isable to generate a signal representative of cardiovascular pressure. Asan example, a PA pressure sensor may be implanted inside either theright or left branch of the pulmonary artery.

FIG. 3 shows an example of a representation of a cardiovascular pressurewaveform 305. The cardiovascular waveform 305 is an example of apulmonary arterial (PA) pressure waveform obtained from a pulmonaryartery pressure sensor signal. In some examples, the cardiovascularpressure waveform 305 is displayed using a strip chart recorder. In someexamples, the cardiovascular pressure waveform is displayed using anelectronic display. The cardiovascular pressure waveform 305 may bedisplayed in real time (e.g., substantially as a cardiovascular pressuresensor provides the cardiovascular pressure signal), or thecardiovascular pressure waveform 305 may be stored and later replayed.Adding one or more annotations to a display of cardiovascular pressurewill aid a caregiver in interpreting the displayed waveform.

FIG. 3 also shows examples of such annotations. The cardiovascularpressure waveform 305 may be displayed together with one or more R-wavemarkers 310 annotating the temporal location of an R-wave of the QRScomplex of an ECG. The R-wave markers 310 can indicate an R-wave andwhether the associated ventricular contraction is a sensed event (VS) ora paced event (VP). The R-wave is only an example of an ECG fiducialmark that may be indicated; one or more other fiducial marks may also beindicated. For example, any part of the P-QRS-T complex may be indicatedby a marker. The R-wave markers 310 shown can also indicate heart rate.ECG markers such as R-wave markers 310 are especially useful insituations where the electrocardiogram (ECG) waveform 315 is notdisplayed. Cardiac arrhythmias may also be indicated by one or morecorresponding markers.

The cardiovascular pressure waveform 305 may be displayed concurrentlywith one or more waveforms or annotations from one or more otherimplantable or external sensors. Examples include, among other things,one or more cardiac electrograms, information from an activity sensor, aposture sensor, a blood gas sensor, a blood chemical sensor, a bloodflow sensor, or a respiration sensor. Presenting visually coherent datafrom one or more other sensors, such as the ECG waveform 315, maysignificantly improve the diagnostic value of the cardiovascularpressure waveform 305.

In some examples, the annotations include one or more respirationmarkers 320. Respiration (breathing) of the subject may modulate thecardiovascular pressure signal. The cardiovascular pressure waveform 305shown in FIG. 3 shows a PA pressure stroke component modulated by arespiration component. The respiration markers 320 can indicate the endof expiration (“END EXP”) and the end of inspiration (“END INSP”) of thesubject. The respiration markers 320 may also indicate the respirationrate (RR) of the subject. The respiration markers 320 may help acaregiver to interpret the respiration modulation of the cardiovascularpressure waveform 305, but they are especially useful if the respiratorymodulation of cardiovascular pressure is removed, such as by processingthe cardiovascular pressure signal with a high-pass filter.

In some examples, the annotations include one or more cardiovascularpressure markers 325. A cardiovascular pressure marker 325 may includeone or more of a cardiovascular pressure parameter value or acardiovascular pressure event such as an end expiratory diastolic (EED)value, an end expiratory systolic pressure, a systolic time interval, arate of change of cardiovascular pressure (dP/dt), a PA pulse pressure,a heart rate, or a central tendency of the cardiovascular pressure suchas the mean cardiovascular pressure.

The end expiratory diastolic value of cardiovascular pressure istypically measured after exhaling but just before inhaling. This valuemay be measured in synchronization with a specified portion of an ECGsignal or a respiration signal, or both. The value can also be measuredat a valley of the cardiovascular pressure stroke component. During thesystolic time interval, the ventricles of the heart are contractingbetween the closing of the mitral valve and the closing of the aorticvalve. The systolic time interval 330 can be determined from an upswingtime in a cardiovascular pressure signal (e.g., the time from whencardiovascular pressure starts to increase until the cardiovascularpressure stops increasing).

The rate of change of cardiovascular pressure may be measured on anupstroke of the cardiovascular pressure stroke component during systole,such as the slope 335 in FIG. 3. The rate of change of cardiovascularpressure may be measured in millimeters of mercury per unit time(mmHg/Δt). PA pulse pressure can be thought of as a measure of adifference between systolic and diastolic cardiovascular pressure, andis typically measured at the end of expiration. Cardiovascular pressure,such as PA pressure, can also be used to indicate heart rate, such as bymeasuring an interval between peaks of the cardiovascular pressurewaveform 305.

The annotations can include a value of the mean or other measure ofcentral tendency of the cardiovascular pressure signal. The value of themean of the cardiovascular pressure may be calculated using one or moreweighted or unweighted combinations of diastolic and systoliccardiovascular pressure. For example, the mean of the cardiovascularpressure can be calculated using two diastolic pressure readings (D) andone systolic pressure reading (S), or

$\begin{matrix}{{Mean} = {\frac{{2D} + {1S}}{3}.}} & (1)\end{matrix}$

The annotations can also include an indication of cardiac arrhythmia,such as determined from values of the cardiovascular pressure signal(e.g., indicative of heart contraction rate) or from a morphology of thecardiovascular pressure signal. For example, a high heart rate mayindicate ventricular tachycardia. In another example, if the morphologyof the cardiovascular pressure signal becomes substantially flat, thismay indicate ventricular fibrillation. In a further example, if thestroke component of a cardiovascular pressure signal is getting pushedhigher, this may indicate ventricular tachycardia.

Cardiovascular pressure waveform annotations are useful in patientdiagnosis. For example, if a patient or subject is experiencing HFdecompensation, left ventricular (LV) filling pressures typicallyincrease. The lungs may couple the higher pressure over to the rightventricle (RV). Because of the difficulties of accessing the LV directlyto make a pressure measurement, an accurate indirect measurement may bedesirable. Because of the pressure coupling through the lungs,cardiovascular pressure may provide a more accurate reading of thisincrease in LV filling pressure than an RV measurement. This, in turn,can help diagnose HF decompensation earlier, thereby helping avoidhospitalization costs associated with an undetected or late-detected HFdecompensation episode.

FIG. 4 is a block diagram of portions of an example of a system 400configured to monitor cardiovascular pressure of a subject. In thisexample, the system 400 includes an external medical device 405 that isconfigured to communicate with an IMD 410. The external medical device405 includes a communication circuit 415 that is configured to receiveinformation associated with cardiovascular pressure from the IMD 410. Insome examples, the cardiovascular pressure information 420 is receivedinto a memory 425. The external medical device 405 can further include adisplay 430, such as to display a waveform 435 that is annotated toindicate one or more events associated with cardiovascular pressure. Theinformation includes any pressure and non-pressure information thatdisplayed temporally with cardiovascular pressure.

In some examples, the cardiovascular pressure information 420 receivedfrom the IMD 410 includes sampled signal data representative ofcardiovascular pressure. The external medical device 405 can display acardiovascular pressure signal waveform together with at least onecardiovascular pressure marker 440 annotating the displayedcardiovascular pressure waveform to indicate a detected event associatedwith cardiovascular pressure. The cardiovascular pressure marker 440 mayinclude a cardiovascular pressure parameter value or a cardiovascularpressure event such as an end expiratory diastolic value (EED), endexpiratory systolic pressure, systolic time interval, a rate of changeof cardiovascular pressure (dP/dt), PA pulse pressure, heart rate, or acentral tendency of the cardiovascular pressure such as the meancardiovascular pressure. The cardiovascular pressure marker 440 may alsoindicate an episode of cardiac arrhythmia, such as determined by themeasured cardiovascular pressure.

In some examples, the external medical device 405 receives sampledsignal data representative of at least one intrinsic heart signal fromthe IMD 410. The external medical device 405 can display an intrinsicheart signal waveform using the sampled signal data together with atleast one cardiovascular pressure marker 440. The cardiovascularpressure marker 440 can annotate the intrinsic heart signal waveform toindicate a detected event associated with cardiovascular pressure. Insome examples, the external medical device 405 receives bothcardiovascular pressure information 420 and information associated withan intrinsic heart signal, and displays a cardiovascular pressure signalwaveform and the intrinsic heart signal waveform together with at leastone cardiovascular pressure marker 440. The cardiovascular pressuremarker 440 annotates at least one of the cardiovascular pressurewaveform and the intrinsic heart signal waveform to indicate a detectedevent associated with cardiovascular pressure. In some examples, theexternal medical device 405 displays at least one cardiovascularpressure marker 440 indicating a detected event associated withcardiovascular pressure and at least one event marker indicating adetected event associated with sensed intrinsic heart activity.

In some examples, the external medical device 405 receives sampledsignal data from the IMD 410 that is representative of at least onesecond sensor signal produced by a second implantable sensor 445. Insome examples, the second implantable sensor 445 is included in the IMD410. The second sensor signal is related to a physiologic condition of asubject and is different from a cardiovascular pressure sensor. Theexternal medical device 405 displays a cardiovascular pressure signalwaveform and a second sensor signal waveform together with at least onecardiovascular pressure marker 440. The cardiovascular pressure marker440 annotates at least one of the cardiovascular pressure signalwaveform and the second sensor signal waveform to indicate an eventassociated with cardiovascular pressure.

In some examples, the second implantable sensor 445 includes a patientactivity sensor. An example of an implantable patient activity sensorincludes an accelerometer. In some examples, the second implantablesensor 445 includes a blood gas sensor. An example of a blood gas sensoris an implantable oxygen saturation sensor. An oxygen saturation sensorproduces an electrical sensor signal associated with changes in thefluid oxygen saturation. Such changes may occur in association with theheart's mechanical activity, contractility, or blood flow.

In some examples, the second implantable sensor 445 includes a bloodchemical sensor. Illustrative examples include a blood electrolytesensor, such as to detect one or more of potassium (K), sodium (Na)calcium (Ca), glucose, or creatinine. In some examples, a blood chemicalsensor detects changes in blood pH. An example of an approach toproviding a chemical sensor in a coronary sinus is found in Kane et al.,U.S. patent application Ser. No. 11/383,933, entitled, “ImplantableMedical Device with Chemical Sensor and Related Methods, filed May 17,2006, which is incorporated herein by reference.

In some examples, the second implantable sensor 445 includes a bloodflow sensor. Examples of a blood flow sensor include a cardiac outputsensor circuit or a stroke volume sensor circuit. Examples of strokevolume sensing are discussed in Salo et al., U.S. Pat. No. 4,686,987,“Biomedical Method And Apparatus For Controlling The Administration OfTherapy To A Patient In Response To Changes In Physiologic Demand,”filed Mar. 29, 1982, and in Hauck et al., U.S. Pat. No. 5,284,136, “DualIndifferent Electrode Pacemaker,” filed May 13, 1991, which areincorporated herein by reference in their entirety.

In some examples, the second implantable sensor 445 includes arespiration sensor. An example of an implantable respiration sensor is atransthoracic impedance sensor to measure minute respiration volume. Anapproach to measuring transthoracic impedance is described in Hartley etal. U.S. Pat. No. 6,076,015 “Rate Adaptive Cardiac Rhythm ManagementDevice Using Transthoracic Impedance,” filed Feb. 27, 1998, which isincorporated herein by reference.

In some examples, the external medical device 405 is communicativelycoupled with at least one external sensor 450. For example, the externalsensor 450 may be communicatively coupled via a Universal Serial Bus(USB) or a serial channel, or the external sensor 450 may becommunicatively coupled to the external medical device 405 wirelessly.The external sensor 450 produces an external sensor signal associatedwith a physiologic condition of a subject. For example, the externalsensor 450 may be an external ECG device. In certain examples, theexternal medical device 405 displays the external sensor signal waveformtogether with at least one cardiovascular pressure marker 440. Thecardiovascular pressure marker 440 annotates the external sensor signalwaveform to indicate a detected event associated with cardiovascularpressure.

The annotated display of one or more waveforms may also be printed, suchas by using a strip chart recorder, for example. In some examples, theexternal medical device 405 includes a programming device for the IMD410. In certain examples, the external medical device 405communicatively coupled to a communication network, such as the internetor a mobile telephone network. The external medical device 405 cancommunicate with the IMD, such as by using a third device, such as arepeater that is in the same room as the subject, for example.

The annotated display of a cardiovascular pressure waveform togetherwith one or more other waveforms, such as an ECG waveform or arespiration waveform, allows a clinician or caregiver to verify that theIMD 410 is working properly, and is properly interpreting cardiac events(e.g., end diastole) or respiratory events (e.g., end expiration).

Cardiovascular pressure can be affected by the subject's posture. Achange in cardiovascular pressure due to a change in posture of apatient may complicate interpretation of one or more events associatedwith cardiovascular pressure. In some examples, the external medicaldevice 405 receives patient posture information from the IMD 410. Forexample, the MD 410 may include a posture sensor. In some examples, thecardiovascular pressure information may only be collected while thesubject is in a particular posture, such as when the subject is layingdown, for example. In some examples, the cardiovascular pressureinformation may be collected while the subject is in multiple detectedpostures, and the cardiovascular pressure measurements are binnedaccording to the different postures, or otherwise associated with aparticular posture. In addition to lying down, examples of theseparticular postures may include the subject being upright, laying his orher left side, or laying on his or her right side. In some examples, thecardiovascular pressure measurements may be binned together with orotherwise associated with a corresponding angle of recumbency. The angleof recumbency may be defined according to an orientation of the thoraxof the subject, such as with respect to a vertical position, or withrespect to a horizontal position.

In certain examples, the external medical device 405 receives thecardiovascular pressure information 420 together with patient postureinformation. The external medical device 405 can display acardiovascular pressure signal waveform together with at least oneindication of the subject's posture. In some examples, the postureindication may be displayed as at least one recumbency angle (e.g.,depending on whether a single axis or multiple axis posture sensor isused).

In some examples, a cardiovascular pressure waveform can be displayedtogether with an indication that includes one or more figures or icons,such as to graphically indicate the subject's posture. An icon of apatient or subject can be displayed (e.g., with respect to vertical) ina two-dimensional orientation, such superior/inferior and lateral forexample. For example, if the patient is standing vertical, as measuredby the posture sensor, the icon would show a standing patient. In someexamples, the angle of recumbency is a default display setting of theexternal medical device 405 and the clinician can optionally view atwo-dimension orientation such as superior/inferior andposterior/anterior. The external medical device 405 may include a userinterface to select between posture indications, such as agraphically-displayed push-button, for example, that enables posturedata to be displayed, or that controls the format of how the posturedata is displayed.

In some examples, the IMD 410 is configured to sense cardiovascularpressure. For example, the IMD 410 may include an implantablecardiovascular pressure sensor 455, such as an implantable PA pressuresensor for example. In some examples, the IMD 410 receives thecardiovascular pressure information from another device. In someexamples, the MD 410 is configured to deliver at least one ofbradycardia therapy, tachycardia therapy, or cardiac resynchronizationtherapy.

As discussed above, the system 400 may include at least one secondimplantable sensor 445 communicatively coupled to the IMD 410. Thesecond implantable sensor 445 produces a second sensor signal related toa physiologic condition of the patient different from cardiovascularpressure. The IMD 410 may include a memory 460. The memory 460 stores atleast one marker 465 indicating at least one detected event associatedwith cardiovascular pressure in relation to sensor information obtainedfrom the second implantable sensor 445.

FIG. 5 is a block diagram of portions of another example of a system 500to monitor cardiovascular pressure of a subject. The system 500 includesan external medical device 505 configured to communicate with a firstIMD 510. The external medical device 505 includes a communicationcircuit 515 configured to receive information from the first IMD 510associated with cardiovascular pressure. In some examples, theinformation associated with cardiovascular pressure 520 is received intomemory 525. The external medical device 505 further includes a display530. The external medical device 505 displays a waveform 535 that isannotated to indicate one or more events associated with cardiovascularpressure. In some examples, the external medical device 505 annotates awaveform 535 using at least one cardiovascular pressure marker 540indicating a detected event associated with cardiovascular pressure.

The system further includes a second IMD 545. The second IMD 545includes a communication circuit 550 and is configured to sensecardiovascular pressure. For example, the second IMD 545 may include animplantable cardiovascular pressure sensor 555. The first IMD 510 isconfigured to receive information associated with cardiovascularpressure from the second IMD 545.

FIG. 6 is a block diagram of portions of another example of a system 600to monitor cardiovascular pressure of a subject. The system 600 includesan IMD 605. The MD 605 includes an implantable cardiovascular pressuresensor interface unit 610. The cardiovascular pressure sensor interfaceunit 610 receives a sensor signal associated with cardiovascularpressure of a subject. In some examples, the IMD 605 may also include acardiovascular pressure sensor 615 communicatively coupled to thecardiovascular pressure sensor interface unit 610. In some examples, thecardiovascular pressure sensor 615 includes an implantable PA pressuresensor. The IMD 605 additionally includes an implantable cardiac signalsensing circuit 620. The implantable cardiac signal sensing circuit 620receives at least one intrinsic heart signal of the subject from atleast one implantable electrode.

The IMD further includes a memory 625 and a trigger detector 630 coupledto the cardiovascular pressure interface unit 610, the implantablecardiac signal sensing circuit 620, and the memory 625. The triggerdetector 630 stores at least one of cardiovascular pressure sensorsignal data or one or more detected cardiovascular pressure-relatedevent annotations in memory 625 in response to a triggering eventdetected from a sensed electrical cardiac signal. In some examples, theannotations include a cardiovascular pressure marker.

In some examples, the trigger detector 630 stores the cardiovascularpressure signal data or the cardiovascular pressure-related eventannotations in memory 625 as a log or logbook. The log may containinformation associated with a cardiovascular pressure-related event suchas the time and the duration of the event. The cardiovascular pressuresignal may be sampled, communicated to the memory, and stored in thelog. In some examples, the trigger detector 630 stores an entry 635 inthe log in a form that includes at least first and second elements, forexample, wherein the first element includes the detected triggeringevent and the second element includes the sampled signal data or the oneor more detected event annotations associated with cardiovascularpressure.

In some examples, the triggering event includes a detected episode ofcardiac arrhythmia that triggers storage of the cardiovascular pressuredata and detected cardiovascular pressure event annotations. The episodeof cardiac arrhythmia may be detected using the implantable cardiacsignal sensing circuit 620, or using a received sensor signal associatedwith cardiovascular pressure, or using both. For example, a high heartrate sensed using the implantable cardiac signal sensing circuit 620 orthe received sensor signal associated with cardiovascular pressure mayindicate ventricular tachycardia. In another example, the morphology ofthe sensor signal associated with cardiovascular pressure may indicateventricular fibrillation or ventricular tachycardia. In some examples,the IMD 605 is configured to deliver at least one of bradycardiatherapy, tachycardia therapy, or cardiac resynchronization therapy.

Storing the cardiovascular pressure signal data and the detected eventannotations may add diagnostic value to a cardiovascular pressuresensor. Many conditions may be transient and therefore not presentduring patient evaluation by a clinician. Historical data associatedwith cardiovascular pressure captured in the log may be useful inpatient diagnosis and treatment.

FIG. 7 is a block diagram of portions of another example of a system 700to monitor cardiovascular pressure of a subject. In this example, thesystem 700 includes an IMD 705. The IMD includes an implantablecardiovascular pressure sensor interface unit 710, an implantablecardiac signal sensing circuit 720, a memory 725, and a trigger detector730 coupled to the cardiovascular pressure sensor interface unit 710,the implantable cardiac signal sensing circuit 720, and the memory 725.The IMD 705 also includes a second sensor 740. The second sensor 740produces a second sensor signal associated with a patient's physiologiccondition that is different from cardiovascular pressure. Examples ofthe second sensor can include any of the sensors discussed herein.

The trigger detector 730 stores at least one of cardiovascular pressuresensor signal data or detected cardiovascular pressure-related eventannotations in memory 725, such as in response to a triggering event. Insome examples, the triggering event includes a detected episode ofcardiac ischemia, such as may be detected using any combination of thesensors.

For example, the implantable cardiac signal sensing circuit 720 mayprovide a wireless ECG. A wireless ECG is a signal approximating thesurface ECG and is acquired without using surface (skin contact) ECGelectrodes. An example of a circuit for wireless ECG sensing isdescribed in commonly assigned, co-pending U.S. patent application Ser.No. 10/795,126, entitled “WIRELESS ECG IN IMPLANTABLE DEVICES,” filed onMar. 5, 2004, which is incorporated herein by reference. For example,the episode of ischemia may include the subject having an S-wave toT-wave (“ST”) interval of the ECG that is elevated, such as by aspecified amount from an ST interval of a baseline ECG. The episode ofischemia may also include a change in cardiovascular pressure. Thetrigger detector 730 stores at least one of cardiovascular pressuresensor signal data or one or more detected cardiovascularpressure-related event annotations in memory 725, for example, as a logentry 735 in response to the detected episode of ischemia. The triggerdetector 730 may also store data associated with a signal from theimplantable cardiac signal sensing circuit 720.

The trigger detector may also store the triggering event detected usingthe wireless ECG. An example of a wireless ECG-based ischemia detectoris discussed in commonly assigned, co-pending U.S. patent applicationSer. No. 11/079,744, entitled “CARDIAC ACTIVATION SEQUENCE MONITORINGFOR ISCHEMIA DETECTION,” filed on Mar. 14, 2005, which is incorporatedherein by reference. In some examples, the second sensor 740 includes aphysical activity sensor, such as an accelerometer. The log entry 735may include information associated with the activity or exertion of thepatient, such as deduced from the activity sensor signal.

In some examples, the second sensor 740 includes a posture sensor. Thetrigger detector can begin storing the data and one or more detectedevent annotations in response to a detected episode of patient syncope,or fainting. The trigger detector 730 can detect syncope using at leastthe posture sensor signal, triggering storage of the cardiovascularpressure information as a log entry in memory 725. The trigger detector730 may also store posture sensor signal related data.

In some examples, the trigger detector 730 can begin storing the data orone or more detected event annotations in response to a detected episodeof postural hypotension. Postural hypotension may be detected using theposture sensor and a change in cardiovascular pressure. If the triggerdetector 730 detects a change in cardiovascular pressure that exceeds aspecified threshold change when a subject is changing posture, such aswhile a patient is moving to a vertical or upright posture, the triggerdetector stores cardiovascular pressure information as a log entry 735in memory 725.

In some examples, the second sensor 740 includes a respiration sensor.The trigger detector 730 can begin storing the data or one or moredetected event annotations in response to a detected episode ofdisordered breathing. Examples of disordered breathing include, amongother things, apnea, hypopnea, periodic breathing, Cheynes-Stokesrespiration, and tachypnea. In some examples, the second sensor 740includes a magnetic field sensor, such as a reed switch. The triggerdetector 730 can begin storing the data or one or more detected eventannotations in response to a detected magnetic field, such as by apatient placing a magnet near the IMD 705. This allows patient-triggeredstorage of the data or one or more detected event annotations, such asin response to the patient experiencing a symptom causing the patientconcern.

In some examples, the system 700 includes an external device 750configured such that it is configured to communicate with the IMD 705.The IMD 705 can communicate a log entry 735 from the memory 725 to theexternal device 750. In some examples, the external device 750 includesa repeater, for example, that is near the subject and that communicateswirelessly with the IMD 705. The repeater can communicate over acommunications or computer network, such as to a remote server, therebyplacing the remote server in communication with the IMD 705 over thenetwork.

In some examples, the system 700 includes a second IMD 755 that isconfigured to sense cardiovascular pressure. The second IMD 755 istypically communicatively coupled to the first IMD 705, and provides asampled cardiovascular pressure signal to the cardiovascular pressuresensor interface unit 710 of the first IMD 705. In some examples, atleast one of the first IMD 705 and the second IMD 755 is configured todeliver at least one of bradycardia therapy, tachycardia therapy, orcardiac resynchronization therapy.

FIG. 8 shows an example of a flow diagram of a method 800 to monitorcardiovascular pressure of a subject. At 805, information associatedwith cardiovascular pressure is communicated from an implantable medicaldevice (IMD) to an external device. At 810, a displayed waveform isannotated on the external device, such as to indicate one or moredetected events associated with cardiovascular pressure. Thecardiovascular pressure waveform may be obtained from cardiovascularpressure sensor.

In some examples, the one or more annotations displayed with thecardiovascular pressure waveform include one or more ECG annotations.The cardiovascular pressure waveform may be displayed with ECG markersor an ECG waveform, or both. The ECG annotations may include anindication of cardiac arrhythmia. In some examples, the method 800includes displaying one or more respiration annotations with acardiovascular pressure waveform. Respiration annotations may include anend of expiration annotation, an end of inspiration annotation, or arespiration rate annotation. In some examples, one or more annotationsdisplayed with the cardiovascular pressure waveform include one or moreposture indications. The cardiovascular pressure waveform can bedisplayed together with at least one indication of patient posture.

In some example, a cardiovascular pressure signal waveform is displayedtogether with at least one cardiovascular pressure marker annotating thecardiovascular pressure waveform to indicate a detected event associatedwith cardiovascular pressure. A cardiovascular pressure marker mayinclude a cardiovascular pressure parameter value or information about aparticular cardiovascular pressure event such as an end expiratorydiastolic value (EED), end expiratory systolic pressure, systolic timeinterval, a rate of change of cardiovascular pressure (dP/dt), PA pulsepressure, heart rate, or a central tendency of the cardiovascularpressure, such as the mean cardiovascular pressure.

In some examples, the method 800 includes displaying a second sensorsignal together with at least one indication of one or more detectedevents associated with cardiovascular pressure. The second sensor signalis produced by a second sensor that is associated with a patient'sphysiologic condition that is different from cardiovascular pressure.Examples of signal sensed by a the second sensor include an intrinsicheart signal, a patient activity signal, a blood gas sensor signal, ablood chemical sensor signal, a blood flow sensor signal, or arespiration signal.

FIG. 9 shows another example of a flow diagram of a method 900 tomonitor cardiovascular pressure of a subject. At 905, one or morecardiac signals representative of intrinsic cardiac activity of apatient are sensed using an IMD. The IMD may include an intrinsiccardiac signal sensing circuit, such as to sense one or more cardiacelectrograms, for example.

At 910, a cardiovascular pressure of a subject is sensed. In someexamples, the IMD includes a cardiovascular pressure sensor. In someexamples, the IMD receives the cardiovascular pressure sensor signalfrom a second device.

At 915, at least one of sampled cardiovascular pressure sensor signaldata or one or more detected cardiovascular pressure-related eventannotations are stored in the IMD, such as in response to a detectedtriggering event detected from a sensed cardiac signal. In someexamples, the data and annotations are stored in a log, for example,included in IMD memory. In some examples, the method 900 includesstoring in the log at least one entry having at least a first elementthat includes the detected triggering event and a second element thatincludes at least one of the sampled cardiovascular pressure sensorsignal data or one or more detected cardiovascular pressure-relatedevent annotations.

In some examples, the triggering event includes an episode of a cardiacarrhythmia, and the sampled cardiovascular pressure sensor signal dataor one or more detected cardiovascular pressure-related eventannotations are stored in response to the IMD detecting the cardiacarrhythmia episode. In some examples, the triggering event includes anepisode of cardiac ischemia and the sampled cardiovascular pressuresensor signal data or one or more detected cardiovascularpressure-related event annotations are stored in response to the IMDdetecting the cardiac ischemia episode.

In some examples, the sampled cardiovascular pressure sensor signal dataand detected one or more cardiovascular pressure-related eventannotations are stored in response to the IMD detecting an episode ofpatient syncope. In some examples, the sampled cardiovascular pressuresensor signal data and one or more detected cardiovascularpressure-related event annotations are stored in response to the IMDdetecting an episode of postural hypotension. In some examples, thesampled cardiovascular pressure sensor signal data and one or moredetected cardiovascular pressure-related event annotations are stored inresponse to the IMD detecting an episode of disordered breathing.

In some examples, the triggering event includes the IMD detecting apresence of a magnetic field, such as by the patient placing a magnetnear the IMD. The sampled cardiovascular pressure sensor signal data andone or more detected cardiovascular pressure-related event annotationsare stored in the log in memory in response to the IMD detecting apresence of a magnetic field. In certain examples, the method 900 caninclude communicating at least one log entry from the IMD to an externaldevice.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. As another example, although the above description hasemphasized the use of a cardiovascular pressure sensor, in otherexamples, other blood pressure sensors or signals can be used inconjunction with the various techniques or apparatuses described herein.Many other embodiments will be apparent to those of skill in the artupon reviewing the above description. The scope of the invention should,therefore, be determined with reference to the appended claims, alongwith the full scope of equivalents to which such claims are entitled. Inthe appended claims, the terms “including” and “in which” are used asthe plain-English equivalents of the respective terms “comprising” and“wherein.” Also, in the following claims, the terms “including” and“comprising” are open-ended, that is, a system, device, article, orprocess that includes elements in addition to those listed after such aterm in a claim are still deemed to fall within the scope of that claim.Moreover, in the following claims, the terms “first,” “second,” and“third,” etc. are used merely as labels, and are not intended to imposenumerical requirements on their objects.

The Abstract is provided to comply with 37 C.F.R. §1.72(b), whichrequires that it allow the reader to quickly ascertain the nature of thetechnical disclosure. It is submitted with the understanding that itwill not be used to interpret or limit the scope or meaning of theclaims. Also, in the above Detailed Description, various features may begrouped together to streamline the disclosure. This should not beinterpreted as intending that an unclaimed disclosed feature isessential to any claim. Rather, inventive subject matter may lie in lessthan all features of a particular disclosed embodiment. Thus, thefollowing claims are hereby incorporated into the Detailed Description,with each claim standing on its own as a separate embodiment.

1. A system comprising: an external medical device configured tocommunicate with a first implantable medical device (IMD), the externalmedical device including: a communication circuit configured to receiveinformation from the first IMD associated with cardiovascular pressure;and a display, wherein the external medical device is configured toannotate a waveform on the display to indicate one or more eventsassociated with cardiovascular pressure.
 2. The system of claim 1,wherein the information associated with cardiovascular pressure includesinformation related to pulmonary arterial (PA) pressure, and wherein theannotation indicates one or more events associated with PA pressure. 3.The system of claim 1, wherein the external medical device is configuredto receive sampled signal data representative of cardiovascularpressure, and to display a cardiovascular pressure signal waveformtogether with at least one cardiovascular pressure marker annotating thedisplayed cardiovascular pressure waveform to indicate a detected eventassociated with cardiovascular pressure.
 4. The system of claim 1,wherein the external medical device is configured to receive subjectposture information from the IMD, and wherein the external medicaldevice is configured to display a cardiovascular pressure signalwaveform together with at least one indication of subject posture. 5.The system of claim 1, wherein the external medical device is configuredto receive sampled signal data representative of at least one intrinsicheart signal from the first IMD, and to display an intrinsic heartsignal waveform together with at least one cardiovascular pressuremarker annotating the intrinsic heart signal waveform to indicate adetected event associated with cardiovascular pressure.
 6. The system ofclaim 5, wherein the external medical device is further configured toreceive sampled signal data representative of cardiovascular pressurefrom the first IMD, and to display a cardiovascular pressure signalwaveform and the intrinsic heart signal waveform together with at leastone cardiovascular pressure marker annotating at least one of thecardiovascular pressure waveform and the intrinsic heart signal waveformto indicate a detected event associated with cardiovascular pressure. 7.The system of claim 1, wherein the external medical device is furtherconfigured to: receive sampled signal data from the first IMD that isrepresentative of at least one second sensor signal produced by a secondimplantable sensor, wherein the second sensor signal is associated witha physiologic condition of a subject and is different from acardiovascular pressure sensor; and display a cardiovascular pressuresignal waveform and a second sensor signal waveform together with atleast one cardiovascular pressure marker annotating at least one of thecardiovascular pressure signal waveform and the second sensor signalwaveform to indicate an event associated with cardiovascular pressure.8. The system of claim 7, wherein the second implantable sensor includesat least one of: a subject activity sensor; a blood gas sensor; a bloodchemical sensor; a blood flow sensor; and a respiration sensor.
 9. Thesystem of claim 6, wherein the external medical device iscommunicatively coupled with at least one external sensor, the externalsensor configured to produce an external sensor signal associated with aphysiologic condition of a subject, and wherein the external medicaldevice is configured to display an external sensor signal waveformtogether with at least one cardiovascular pressure marker annotating theexternal sensor signal waveform to indicate a detected event associatedwith cardiovascular pressure.
 10. The system of claim 1, wherein theexternal medical device is configured to receive information associatedwith sensed intrinsic heart activity and information associated withcardiovascular pressure from the first IMD, and to display at least onecardiovascular pressure marker indicating a detected event associatedwith cardiovascular pressure and at least one event marker indicating adetected event associated with sensed intrinsic heart activity.
 11. Thesystem of claim 1, further comprising the first IMD, wherein the firstIMD is configured to sense cardiovascular pressure.
 12. The system ofclaim 11, further comprising: at least one second implantable sensorconfigured to produce a second sensor signal related to a physiologiccondition of the subject different from cardiovascular pressure; andwherein the first IMD includes a memory and is configured to storemarkers indicating detected events associated with cardiovascularpressure in relation to sensor information obtained from the secondimplantable sensor.
 13. The system of claim 1, further comprising asecond IMD, the second IMD including a communication circuit andconfigured to sense cardiovascular pressure, and wherein the first MD isconfigured to receive information associated with cardiovascularpressure from the second IMD.
 14. The system of claim 1, wherein thefirst IMD is configured to deliver at least one of bradycardia therapy,tachycardia therapy, and cardiac resynchronization therapy.
 15. A systemcomprising: a first implantable medical device (IMD) comprising: animplantable cardiovascular pressure sensor interface unit, thecardiovascular pressure interface unit configured to receive a sensorsignal associated with cardiovascular pressure of a subject; animplantable cardiac signal sensing circuit configured to receive atleast one intrinsic heart signal from at least one implantableelectrode; a memory; and a trigger detector coupled to thecardiovascular pressure sensor interface unit, the implantable cardiacsignal sensing circuit, and the memory, wherein the trigger detector isconfigured to store at least one of cardiovascular pressure sensorsignal data and detected cardiovascular pressure-associated eventannotations in response to a triggering event detected from a sensedelectrical cardiac signal.
 16. The system of claim 15, wherein theimplantable cardiovascular sensor interface unit includes a pulmonaryarterial (PA) pressure sensor interface unit, and wherein the triggerdetector is configured to store at least one of PA pressure sensorsignal data and detected PA pressure-associated event annotations. 17.The system of claim 16, further comprising a PA pressure sensorcommunicatively coupled to the implantable PA pressure sensor interfaceunit.
 18. The system of claim 15, further comprising a second IMDcommunicatively coupled to the first IMD, wherein the second IMD isconfigured to sense cardiovascular pressure.
 19. The system of claim 15,wherein the first IMD is configured to deliver at least one ofbradycardia therapy, tachycardia therapy, and cardiac resynchronizationtherapy.
 20. The system of claim 15, wherein the trigger detector isconfigured to begin storing the data and detected event annotations inresponse to a detected episode of cardiac arrhythmia.
 21. The system ofclaim 15, wherein the trigger detector is configured to begin storingthe data and detected event annotations in response to a detectedepisode of cardiac ischemia.
 22. The system of claim 15, wherein thefirst IMD includes a posture sensor coupled to the trigger detector, andwherein the trigger detector is configured to begin storing the data anddetected event annotations in response to a detected episode of patientsyncope.
 23. The system of claim 22, wherein the first IMD includes aposture sensor coupled to the trigger detector, and wherein the triggerdetector is configured to begin storing the data and detected eventannotations in response to a detected episode of postural hypotension.24. The system of claim 22, wherein the first IMD includes a respirationsensor coupled to the trigger detector, and wherein the trigger detectoris configured to begin storing the data and detected event annotationsin response to a detected episode of disordered breathing.
 25. Thesystem of claim 22, wherein the first IMD includes a magnetic fieldsensor coupled to the trigger detector, and wherein the trigger detectoris configured to begin storing the data and detected event annotationsin response to a detected magnetic field.
 26. The system of claim 22,wherein the trigger detector is configured to store at least one entryin a log that includes at least first and second elements, wherein thefirst element includes the detected triggering event and the secondelement includes at least one of sampled signal data and detected eventannotations associated with cardiovascular pressure.
 27. The system ofclaim 26, further including an external device configured to communicatewith the first IMD, and wherein the first IMD is adapted to communicateat least one log entry to the external device.
 28. The system of claim27, wherein the external device includes a remote server incommunication with the first IMD over a communications or computernetwork.
 29. A method comprising: communicating information associatedwith cardiovascular pressure from an implantable medical device (IMD) toan external device; and annotating a displayed waveform on the externaldevice to indicate one or more detected events associated withcardiovascular pressure.
 30. The method of claim 29, whereincommunicating includes communicating information related to PA pressureand wherein annotating includes annotating to indicates one or moreevents associated with PA pressure.
 31. The method of claim 29, furtherincluding displaying a cardiovascular pressure signal waveform togetherwith at least one cardiovascular pressure marker annotating thecardiovascular pressure waveform to indicate a detected event associatedwith cardiovascular pressure.
 32. The method of claim 31, furtherincluding displaying a cardiovascular pressure signal waveform togetherwith at least one indication of patient posture.
 33. The method of claim29, further including displaying a second sensor signal together with atleast one indication of one or more detected events associated withcardiovascular pressure, wherein the second sensor is related to aphysiologic condition of the subject different from cardiovascularpressure.
 34. The method of claim 33, wherein the displaying the secondsensor signal includes displaying one or more of: a sensed intrinsicheart signal; an activity sensor signal; a blood gas sensor signal; ablood chemical sensor signal; a blood flow sensor signal; and arespiration signal.
 35. A method comprising: sensing one or more cardiacsignals representative of intrinsic cardiac activity of a subject usingan implantable medical device (IMD); sensing cardiovascular pressure ofthe subject; and storing at least one of sampled cardiovascular pressuresensor signal data and detected cardiovascular pressure-related eventannotations in the IMD in response to a detected triggering eventdetected from a sensed cardiac signal.
 36. The method of claim 35,wherein sensing cardiovascular pressure includes sensing PA pressure,and wherein storing includes storing at least one of sampled PA pressuresensor signal data and detected PA pressure-related event annotations.37. The method of claim 35, wherein storing includes storing the sampledcardiovascular pressure sensor signal data and detected cardiovascularpressure-related event annotations in response to the IMD detecting anepisode of cardiac arrhythmia.
 38. The method of claim 35, whereinstoring includes storing the sampled cardiovascular pressure sensorsignal data and detected cardiovascular pressure-related eventannotations in response to the IMD detecting an episode of cardiacischemia.
 39. The method of claim 35, wherein storing includes storingthe sampled cardiovascular pressure sensor signal data and detectedcardiovascular pressure-related event annotations in response to the IMDdetecting an episode of patient syncope.
 40. The method of claim 35,wherein storing includes storing the sampled cardiovascular pressuresensor signal data and detected cardiovascular pressure-related eventannotations in response to the IMD detecting an episode of posturalhypotension.
 41. The method of claim 35, wherein storing includesstoring the sampled cardiovascular pressure sensor signal data anddetected cardiovascular pressure-related event annotations in responseto the IMD detecting an episode of disordered breathing.
 42. The methodof claim 35, wherein storing includes storing the sampled cardiovascularpressure sensor signal data and detected cardiovascular pressure-relatedevent annotations in response to the IMD detecting a presence of amagnetic field.
 43. The method of claim 35, wherein storing includesstoring at least one entry in a log having at least a first element thatincludes the detected triggering event and a second element thatincludes at least one of the sampled cardiovascular pressure sensorsignal data and detected cardiovascular pressure-related eventannotations.
 44. The method of claim 35, further including communicatingat least one log entry from the IMD to an external device.